From 9da76e0003c9a954a45df8333829dbd4cff27be2 Mon Sep 17 00:00:00 2001
From: ephphatha <ephphatha@thelettereph.com>
Date: Sat, 31 Dec 2022 23:34:35 +1100
Subject: [PATCH] Update CheckReflect to return applied damage

Instead of modifying the damage value by reference
---
 Source/engine/random.hpp | 24 ++++++++++++++++++++++++
 Source/monster.cpp       | 13 ++++++++-----
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/Source/engine/random.hpp b/Source/engine/random.hpp
index 5a629a527..34c01c60f 100644
--- a/Source/engine/random.hpp
+++ b/Source/engine/random.hpp
@@ -84,4 +84,28 @@ const T PickRandomlyAmong(const std::initializer_list<T> &values)
 	return *(values.begin() + index);
 }
 
+/**
+ * @brief Generates a random non-negative integer
+ *
+ * Effectively the same as GenerateRnd but will never return a negative value
+ * @param v upper limit for the return value
+ * @return a value between 0 and v-1 inclusive, i.e. the range [0, v)
+ */
+inline int32_t RandomIntLessThan(int32_t v)
+{
+	return std::max<int32_t>(GenerateRnd(v), 0);
+}
+
+/**
+ * @brief Randomly chooses a value somewhere within the given range
+ * @param min lower limit, minumum possible value
+ * @param max upper limit, either the maximum possible value for a closed range (the default behaviour) or one greater than the maximum value for a half-open range
+ * @param halfOpen whether to use the limits as a half-open range or not
+ * @return a randomly selected integer
+ */
+inline int32_t RandomIntBetween(int32_t min, int32_t max, bool halfOpen = false)
+{
+	return RandomIntLessThan(max - min + (halfOpen ? 0 : 1)) + min;
+}
+
 } // namespace devilution
diff --git a/Source/monster.cpp b/Source/monster.cpp
index f85c1ba39..8395c5c95 100644
--- a/Source/monster.cpp
+++ b/Source/monster.cpp
@@ -1106,19 +1106,20 @@ void MonsterAttackMonster(Monster &attacker, Monster &target, int hper, int mind
 	}
 }
 
-void CheckReflect(Monster &monster, Player &player, int &dam)
+int CheckReflect(Monster &monster, Player &player, int dam)
 {
 	player.wReflections--;
 	if (player.wReflections <= 0)
 		NetSendCmdParam1(true, CMD_SETREFLECT, 0);
 	// reflects 20-30% damage
-	int mdam = dam * (GenerateRnd(10) + 20L) / 100;
+	int mdam = dam * RandomIntBetween(20, 30, true) / 100;
 	ApplyMonsterDamage(monster, mdam);
-	dam = std::max(dam - mdam, 0);
 	if (monster.hitPoints >> 6 <= 0)
 		M_StartKill(monster, player);
 	else
 		M_StartHit(monster, player, mdam);
+
+	return mdam;
 }
 
 int GetMinHit()
@@ -1192,8 +1193,10 @@ void MonsterAttackPlayer(Monster &monster, Player &player, int hit, int minDam,
 	int dam = (minDam << 6) + GenerateRnd(((maxDam - minDam) << 6) + 1);
 	dam = std::max(dam + (player._pIGetHit << 6), 64);
 	if (&player == MyPlayer) {
-		if (player.wReflections > 0)
-			CheckReflect(monster, player, dam);
+		if (player.wReflections > 0) {
+			int reflectedDamage = CheckReflect(monster, player, dam);
+			dam = std::max(dam - reflectedDamage, 0);
+		}
 		ApplyPlrDamage(player, 0, 0, dam);
 	}